About half a million young adults (YA; defined here as 19-25 years old) enter substance abuse treatment each year, but despite recognizing addiction as a chronic disease, little research has examined models of continuing care for this age group. Costly residential treatments discharge YAs with referral to outpatient care or self-help groups, but many do not use or minimally participate in them. Relapse rates are high after residential treatment and many parents feel unsupported and poorly prepared when their child is discharged and returns to their home. Effective continuing care is needed to engage YAs, prepare and support parents, and halt progression to a debilitating adult disease. Cost-efficient, easily disseminated, sustainable continuing care models must be designed. This R21 application proposes to develop and pilot test Home-based Continuing Care (HCC) for YAs leaving residential treatment. HCC will combine two efficacious approaches: Telephone-based CC (TCC) and Contingency Management (CM). A remote, telephone-based model would allow delivery of HCC from a small cadre of providers, reducing challenges of dissemination. The specific aims of the research are to explore the: 1) Acceptability of HCC to parents and YAs; 2) Feasibility of sustaining the intervention; 3) Feasibility of conducting a randomized controlled trial (RCT) of HCC; and 4) Preliminary estimation of HCC efficacy and need for a RCT. During Phases 1 & 2 of the three-phase project, parents and YAs will be recruited from residential treatment programs and parent support groups. Phase 1 will survey 50 parents and 50 YAs to develop informed judgments on the acceptability of HCC procedures and identify and find solutions to barriers to parent and YA participation. In Phase 2 a pilot study with baseline, 16- and 32 week assessments will be piloted with 20 parent-YA pairs randomly assigned to HCC or continuing services as usual (SAU). While the YA is in residential treatment HCC parents will receive training in communication, urine testing procedures, and CM so that after discharge they can partner with the HCC program to support the YA's recovery. With therapist monitoring and feedback, HCC parents will administer randomly scheduled home- based urine tests and provide incentives for verified abstinence and engagement in the continuing service plan developed by the residential program. HCC YAs will receive TCC with regular therapist contact by text message and/or phone to assess relapse risk and provide brief counseling. We will explore: 1) HCC accept- ability by examining HCC engagement, retention and treatment satisfaction; 2) sustainability by estimating HCC costs and asking parents what they would be willing to pay for it; 3) RCT feasibility by examining recruitment rate, treatment fidelity, and follow-up retention in both groups; and 4) preliminary efficacy and need for a RCT by examining (a) estimated effect size in conjunction with (b) assessment by parents, YAs, and addiction experts of the clinical importance of outcomes. In Phase 3 we will review project results with Parent and Youth Advisory Boards and the expert panel and make final decisions on need and feasibility of an RCT.